Buttonhole sewing mechanism in zigzag sewing machines



Nov. 9, 1965 TAMoTSU KoJlMA ETAL 3,215,385

BUTTONHOLE SEWING' MECHANISM IN ZIGZAG SEWING MACHINES Filed Deo. 7,1962 2 Sheets-Sheet l Nov. 9, 1965 TAMoTsU KoJxMA ETAL 3,216,385

BUTTONHOLE SEWING MECHANISM IN ZIGZAG SEWING MACHINES Filed Dec. 7, 19622 Sheets-Sheet 2 United States Patent Office 3,216,385 Patented Nov. 9,1965 3,216,385 BUTTONHOLE SEWING MECHANISM IN ZIGZAG SEWING MACHINESTamotsu Kojima, Honjyocho, Higashi-nada-ku, Kobe, Hyoga Prefecture,Japan, assignor to Yoshio Doi, Osaka, Japan Filed Dec. 7, 1962, Ser. No.243,119 Claims priority, application Japan, Dec. 11, 1961, @i6/45,149 1Clair-n. (Cl. 112-1S8) This invention relates to an improvement inzigzag sewing machines of the conventional type having a mechanism forzigzag sewing by means of transverse oscillations of the needle bar, amechanism for adjusting the amplitude of lateral oscillation of theneedle bar and a mechanism for reversing the direction of material feed,and more specifically, this invention has for an object to provide abuttonhole sewing means adapted for use on such type of zigzag sewingmachines to permit the machines to perform not only zigzag sewing ofvarious patterns but also buttonhole sewing by means of the manipulationof an operating lever.

The principal object of the present invention is to provide a uniquebuttonhole sewing mechanism whereby the length and width of a buttonholesea-m can be adjusted freely according to the size of buttonhole. Forexample, for the sewing of a small buttonhole, the amplitude of theswinging movement of the needle bar is made small so that a seam ofsmall width may be produced and for the sewing of a large buttonhole,the amplitude of the needle movement is made larger to produce abuttonhole seam of large width.

Another object of this invention is to provide a new buttonhole sewingmeans so devised that the length of the so-called barring stitches to beproduced at the upper and lower terminal ends of a buttonhole can beadjusted according to the size of buttonhole and further that thedistance from the edge of a seam n one side of a buttonhole to the edgeof a seam on the opposite side can be made long or short as desired.

In order to permit a sewing machine of the type described to accomplishthe aforementioned functions easily and accurately, a unique cam member,an arm piece and a spring means are mounted on a control shaft which isrotatably supported in the machine frame for buttonhole sewingoperation. The said cam member is engaged by a lever in a zigzag-motionadjusting means connected with a zigzag-motion generating mechanism, thesaid arm piece being disposed to be engaged by an operating armconnected with a center-line shifting mechanism and the said springmeans being linked to the feeding mechanism, while the said controlshaft for buttonhole sewing operation is disposed in an eccentricallyrotatable sleeve means. Under such arrangement, when the control shaftis rotated eccentrically by turning the sleeve means, the cam and armpiece mounted on the shaft are caused to change their operativepositions to influence the movements of the zigzag-motion generatingmechanism and the arm member for center-line shifting, therebypermitting the sewing of buttonholes of various sizes accurately andeasily.

The nature of this invention will be more clearly understood byreference to the accompanying drawings, forming a part of the presentapplication and illustrating unique elements and means employed toaccomplish the functions of the present invention. In the drawings:

FIG. l represents a front elevation, in vertical section, of a sewingmachine provided with the improved buttonhole sewing mechanism of myinvention.

FIG. 2 represents a plan view, in cross-section, of the sewing machineshown in FIG. 1.

FIG. 3 represents a cross-sectional view of the mechanism on the sectionline III- III of FIG. 1.

FIG. 4 represents a front View, showing the connection of a controlshaft for buttonhole sewing operation with a part of a zigzag-motiongenerating mechanism.

FIG. 5 represents a plan view, showing the connection of a lever forzigzag-motion adjustment with a centerline shifting mechanism.

FIG. 6 represents a perspective view of an operating arm for center-lineshifting.

FIG. 7 represents a front View, showing a cam and an arm piece mountedon the control shaft in the upwardly adjusted positions as actuated bythe eccentric movement of the control shaft.

FIG. 8 represents a front view, showing the elements in FIG. 7 in thedownwardly adjusted positions as actuated by the reverse movement of thecontrol shaft.

FIG. 9 represents diagrammatically a seam produced on the left border ofa buttonhole.

FIG. 10 represents diagrammatically a seam produced on the right borderof the buttonhole.

All of the drawings illustrate only those elements and devices that areessential to my invention and the other component elements not relatedto the present invention are omitted from the drawings. The samereference numerals and characters refer to the same parts in thedrawmgs.

The bracket-arm A, hollow standard B and bed plate C are of the sameshapes and constructions as those used in the conventional zigzag sewingmachines and similarly, other component elements mounted inside thoseparts, such as a zigzag-motion generating mechanism in which atriangular cam E driven by the upper shaft D rocks an oscillator memberH having its one end pivotally secured at the point G to a movable arm Ffor center-line shifting, the rocking motion of the said oscillator Hbeing transmitted to the needle bar L through a connecting rod M whichis operatively connected with the oscillator H by means of a linkinglever K having its one end disposed in an arcuate groove H of theoscillator H, a means for moving a shuttle in time with the lateralrocking movement of the needle bar, and an amplitude adjusting mechanismin which a cam shaft P driven by the upper shaft D carries thereon anassembly of cams of different shapes and the said cam unit is engaged bya cam-follower lever R which is pivotally secured at its midpoint R foradjusting the width of zigzag seams to the desired degree, are the sameas those in any conventional zigzag sewing machine.

Now, a movable arm F which supports at its end an oscillator H forming apart of the zigzag-motion generating mechanism, is pivotally secured tothe upper end of an axis 3. Fixedly secured to the lower end of the axis3 is an operating arm 4 provided at its end with a slope 26 which isengaged by the beaked end of an arm piece 2 carried by a control shaft1.

Mounted on the control shaft 1 which is rotatably supported in themachine frame is a cam 8, the periphery of which comprises a low portiona, the first shoulder portion b which is substantially higher than thesaid lower portion a, a high portion c and the second shoulder portion bwhich is also substantially higher than the said lower portion a. Thecam 8 is constantly engaged by the beaked end (constituting a camfollower) of a lever 10 which is pivotally secured at its approximatemid-point 9 to a part of the machine frame and has its other endconnected by means of a linking member 12 to a rod 11 slidably disposedon the machine frame.

The slidable rod 11 is operatively linked by means of a protrusion 16carried thereon to a hooked member 14 which is pivotally secured bymeans of a screw 15 to a swingable plate means 13 for zigzag amplitudeadjustment. The swingable plate means 13 has its one end operativelyconnected with the oscillator H through the medium of a linking lever Kwhich has its base end rigidly secured to a vertical shaft T and itsother end disposed in anv arcuate groove H of the oscillator H. Providedon the upper surface of the swingable plate means 13 is a roller member19 engaging in the forked end of a cam-follower lever R.

On the other hand, a spring means 5 is rigidly secured to the inner endof the control shaft 1 and the said spring 5 has its free end connectedto a projection 7 provided on one side of a regulator member 6 providedon a bifurcated rod V for material feeding. The control shaft 1 carriesat its external end a manipulating lever 20 which is supported in a hole23 provided eccentrically in a bushing 2 rotatably interposed in asleeve 21 secured to the machine frame by means of a screw. Therotatable bushing 22 carries at its external end a handle 24 whichprojects downwardly through a cap member 25 covering the end portion ofthe sleeve 21.

Under the arrangement thus described, as long as the beaked end of thelever is held in contact with the lower portion a of the cam 8, abuttonhole sewing operation is rendered ineffective and only the sewingof decorative seams is performed by means of the zigzag sewingmechanism. For the switchover from ordinary zigzag sewing to buttonholesewing operation, the cam unit mounted on the shaft P is released fromengagement with the cam-follower lever R to render the lever Rinoperative and thereafter, the manipulating lever 20 is rotated tobring the first shoulder portion b of the cam 8 into contact with thebeaked end of the lever 10, whereupon the latter is caused to swingupwardly. This swinging motion of the lever 10 is transmitted by meansof the slidable rod 11 operatively connected thereto and the hookedmember 14 engaging the protrusion 16 of the rod 11 to the swingableplate means 13 to swing the latter slightly, thereby influencing thezigzag-motion generating mechanism to adjust the amplitude or volume ofoscillation of the oscillator H to the desired degree for buttonholesewing. The adjusted oscillating motion of the oscillator H will betransmitted to the needle bar L by means of a connecting rod Moperatively connected with both the oscillator H and the needle bar L,to perform zigzag sewing of one border, for example, the lefthand borderof a buttonhole.

During the above sewing operation, the feeding mechanism is set in aposition for forward feeding, and as soon as the sewing of the left-handborder e is completed, the manipulating lever 20 is rotated to bring thehigh portion c of the cam 8 into contact with the beaked end of thelever 10, whereupon the latter is caused to swing largely. This swingingmotion of the lever 10 is transmitted by means of the slidable rod 11and the hooked member 14,

as already described, to the swingable plate means 13 to swing thelatter largely, influencing the zigzag-motion generating mechanism toadjust the volume of oscillation of the oscillator H to a large extent,the said adjusted motion being transmitted to the needle bar L, causingit to shift its position from the left-hand side of the buttonhole tothe right-hand side, to effect a barring stitch f at the lower terminalend of the buttonhole. Since the material is being fed in forwarddirection, the barring stitching will be effected several times.

Upon completion of the barring stitches at the lower terminal end, themanipulating lever 20 is rotated again to bring the second shoulderportion b of the cam S into contact with the beaked end of the lever 10and at the same time, the spring means 5 presses the protrusion 7 of thefeed regulator member 6 to rotate the latter, whereupon the bifurcatedrod V is changed to its reverse feeding position. Simultaneously, thearm piece 2 provided on the control shaft 1 is moved to press the slope26 of the operating arm 4 to swing the latter, whereupon the movable armF pivotally mounted on the axis 3 is caused to swing about the pivotaxis 3, thereby shifting the pivot point G of the oscillator H at whichit is pivotally secured to the movable arm F. By the shifting of thepivot point G which determines the centerline of zagzag seam, thecenter-line of zig-zag seam is shifted, which means that the needle barL is shifted to the outer edge of the opposite side of the buttonhole.

With the material being fed in backward direction, the zigzag sewing ofthe right border of the buttonhole is performed in the same manner andin the same seam width as done before when the lever 10 was held incontact with the first shoulder portion b of the cam 8. Upon completionof zigzag seam g for the right border of the buttonhole the manipulatinglever 20 is rotated in reverse direction to bring the high portion c ofthe cam 8 back into contact with the beaked end of the lever 10whereupon the needle bar L is caused to effect several barring stitchesh at the upper terminal end of the buttonhole in the same manner as donebefore for the lower terminal end, thus completing the whole buttonholesewing operation.

According to the present invention, the width of buttonhole seam and thedistance from the edge of a seam on one side of a buttonhole to the edgeof a seam on the opposite side thereof can be adjusted, for the sewingof buttonholes of various sizes. This unique function is accomplished byfirst turning the handle 24 secured to the rotatable bushing 22. Uponrotation of the bushing 22, the control shaft 1 disposed eccentricallyin the former is moved up and down, causing the cam 8 and arm piece 2mounted thereon to move up or down, whereupon the position of the cam 8in relation to the pivot axis 9 of the lever 10 is shifted farther ornearer, thereby varying the amplitude of the swinging motion of thelever 10 engaging therewith. The change in the amplitude of thisswinging motion results in a variation in the amplitude of the operativemotion of the zigzag-motion adjusting means and hence the amplitude ofthe swinging motion of the oscillator H forming a part thereof,whereupon the width of zigzag seam is adjusted to various degrees.

On the other hand, when the arm piece 2 is moved up or down, theposition of its engagement with the operating arm 4 for center-lineshifting is shifted up or down, varying the amplitude of the swingingmotion of the operating arm 4, whereupon the amplitude of shifting ofthe centerline is adjusted accordingly.

I shall now describe in further detail the operations of theabovementioned elements. When the handle 24 is turned upward, thecontrol shaft 1 and hence the cam 8 and the arm piece 2 move upward,whereupon the beaked end of the lever 10 is pressed upward. The swingingmotion of the lever 1t) in its upwardly adjusted position causestheslidable rod 11 to move backward by a long distance, which thenactuates the swinging movement of the swingable plate means 13 by meansof the hooked member 14 connected therewith. By the swinging motion ofthe plate means 13, the amplitude of the operative motion of thezigz-ag-motion generating mechanism is adjusted and the amplitude of theswinging motion of the oscillator H is made greater to produce a zigzagseam of large width.

On the other hand, by the simultaneous upward movement of the arm piece2, the position of the contact of the Said -arm piece 2 with thespread-out slope 26 of the arm 4 is shifted upward, thereby swinging thearm 4 largely about the axis 3, whereupon the movable arm F rigidlyfixed to the upper end of the axis 3 is caused to swing largely aboutthe axis 3. With the swinging movement of the movable arm F, theposition of the pivot point G at which the oscillator H is pivotallysecured to the arm F is shifted and thus, the center-line of zigzagmovement is shifted by a long distance from the left-hand side of thebuttonhole to the right-hand side. Herein lies the reason why thepresent improved mechanism is suitable for the sewing of largebuttonholes.

Next, when the handle 24 is turned downward, the control shaft 1 andhence the cam 8 and the arm piece 2 mounted thereon move downward asshown in FIG. 8, whereupon the lever cooperable with the cam 8 and alsothe operating arm 4 contacted by the arm piece 2 are caused to move in amanner opposite to that when the handle 24 was turned upward, therebycontracting the amplitude of zigzag motion -and also the amplitude ofcenter-line shifting motion, Which naturally results in a diminution ofthe distance from the edge of a seam on one side of a buttonhole to theedge of a seam on the opposite side. Herein lies the reason why thepresent improved mechanism is suitable also for the sewing of smallbuttonholes.

Regarding the shifting of the center-line of a seam in the aboveoperation, since the slope 26 of the operating lever or arm 4 engaged bythe arm piece 2 is widened towards its lower end, the amplitude of theswinging movement of the operating -arm 4 when the arm piece 2 engagedthe lower portion of the slope 26 differs from that when the tip of thearm piece 2 engaged the upper portion of the slope 26. In other words,the volume of the swinging movement of the operating arm 4 variesexactly according to the difference in height between the upper andlower portions of the slope 26 where the tip of the arm piece 2contacts. It will thus be known that the volume of the shifting of thecenter-line varies by the difference in height between the upper landlower portions of the slope 26.

As described herein, by the manipulation of the handle 24, whichactuates the rotation of the rotatory bushing 22, the control shaft 1supported in the hole provided eccentrically in the said bushing 22 ismoved up or down, actuating similar movements of the cam 8 and the armpiece 2 mounted on the shaft 1 to enlarge the width of zigzag seam andthe distance from the seam on one side to the seam on the opposite sidefor the sewing of large buttonholes and to `diminish the seam width anddistance for the sewing of small buttonholes. This unique function makesthe present invention the most ideal of all for buttonhole `sewingoperation.

Having thus described the nature of my invention, what I claim hereinis:

In a zigzag sewing machine of the type having a frame, a reciprocatingand swingable needle bar, a reversible material feeding means, a driveshaft for reciprocating said needle bar and driving said feeding means,mechanism driven by said drive shaft for swinging said needle bar toprovide a zigzag stitch and means to adjust the amplitude of swingingmovement of said needle bar to vary the width of the stitch, abuttonhole sewing device comprising an eccentric bushing rotatablymounted on said frame, `a iinger-engaging knob on said bushing, acontrol shaft rotatably mounted in said bushing, a cam fixed on saidcontrol shaft, first, second, third and fourth lobes on said cam, alinger engaging knob fixed to said control shaft, a cam follower leverengaging said cam, linkage means connecting said lever and saidamplitude adjusting means, an arm fixed to said control shaft, a secondlever having a beveled surface thereon disposed in the path of movementof said arm, means connecting said second lever and said swingingmechanism, whereby upon rotation of said bushing to move the axis ofsaid control shaft, the effective length of said follower lever will bevaried to vary the degree of adjustment of stitch width and the point ofengagement of said arm with said beveled surface will be changed to varythe degree of change of the stitch center line upon rotation of saidcontrol shaft to certain positions to change the stitch center line, andmeans connecting said control shaft and said feeding means to reversethe direction of `feed upon rotation of said control shaft to certainpositions, whereby with said follower lever engaging said first lobesaid machine will sew a conventional zigzag stitch, upon rotation ofsaid control shaft to engage said follower lever with said second lobesaid machine will sew a wider zigzag stitch for one side of a buttonholeseam, upon rotation of said control shaft to engage said follower leverwith said third lobe and change the stitch center line said machine willsew a still wider zigzag barring stitch at one end of said button holeseam, upon rotation of said control shaft to engage said follower leverwith said fourth lobe, reverse the direction of `feed land furtherchange the stitch center line said machine will sew a zigzag stitchcorresponding to said first mentioned wider stitch in the reversedirection for the opposite side of said buttonhole seam and upon reverserotation of said control shaft to again engage said follower lever withsaid third lobe and change the stitch center line to the iirst changedposition said machine will sew a zigzag barring stitch at the oppositeend of said buttonhole seam corresponding to said iirst mentionedbarring stitch.

References Cited bythe Examiner UNITED STATES PATENTS 2,623,487 12/52Marasco 112-159 2,990,793 7/61 Zink etal 112-158 3,033,138 5/62 Bono112-158 3,104,638 9/63 Engel 112-158 3,108,555 10/63 Engel 112-158ROBERT V. SLOAN, Primary Examiner.

JORDON FMNKLIN, Examiner.

